This invention relates generally to measuring tools and more particularly concerns a measuring tool constructed of a flexible material. In the past, measuring tools have usually been constructed of non-flexible materials so as to avoid warping, and variations in measurements due to flexing. Non-flexible materials, such as metals and the like, provide rigidity and additionally wear well when subjected to use on a working surface and the nicks and bumping of other tools in a workman's toolbox. However, due to the high costs of metals, it is desirable to provide a measuring tool made of a lower cost flexible material.
In constructing a measuring tool of flexible material, a common way is by injection molding plastics. However, with injection molding the tool cannot be made excessively thick so as to withstand the wear and hazards mentioned above, since if it is made too thick, the processing time in cooling the plastic and the cost of material increase the cost of the tool to that of metal measuring tools. Moreover, when the tool is made of thick layers of plastics, shrinkage and warpage in cooling become a serious problem in providing for precise measuring indications. Thus, it is necessary to maintain the measuring tool as thin as possible in order to avoid shrinkage, warpage, increased costs of materials and increased processing time. However, as a tool is made thinner, the flexible nature of the plastic increases the problems in using the tool to mark or align.
Likewise the marking indicia for the measurement scales must be raised from the surface of the measuring tool in order to avoid excessive thickness. If they are imbedded or depressed into the structure of the tool, then the structure would have to be thicker. Unfortunately, since the raised marking indicia must be thin so they can provide a precise indication of the measurement alignment, they are even more prone to being worn off, abraded, chipped, broken and the like during use and storage in a toolbox.
Still another problem in constructing a measuring tool of a flexible material is that such tools are commonly moved slidably back and forth across wood or other work surfaces in order to mark the work surface, used as a guide for saw blades, and used in other abrasive environments. If raised marking indicia are allowed to slide across the surface being measured they will rapidly be abraded and worn off when the flexible material is used. Moreover, rather than simply putting the raised marking indicia on the upper surface of the tool and leaving the lower surface flat for sliding on the work surface it is more desirable to have as many different scales or different measuring indications on the tool. Thus, it is usually necessary to have marking indicia on both the upper and lower surface of the tool.
Accordingly, it is the primary aim of the invention to provide a measuring tool constructed of a flexible material with raised marking indicia which are not subject to excessive wear, premature breaking or abrasion of the measuring indicia, while allowing the thickness of the tool to be kept as thin as possible.
A further object is to provide a measuring tool constructed of a flexible material with raised marking indicia wherein the marking indicia do not slide back and forth on the work surfaces which are measured.
Still another object of the invention is to provide a measuring tool with raised marking indicia on both upper and lower surfaces of the tool.
Still another object of the invention is to provide a measuring tool with marking indicia constructed of a flexible material which will minimize the problem of parallax.